Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A link state protocol controlled Ethernet network having data plane multicast capability, the network comprising: a first node configured to issue a frame containing a control message signifying a local topology change, the frame being addressed to a control plane specific multicast group address; a second node configured: to receive the frame containing the control message; to perform a reverse path forwarding check on the frame to determine if the frame arrived at the second node on a port expected for multicast frames issued by the first node; to discard the frame immediately when the frame fails the reverse path forwarding check; and when the frame passes the reverse path forwarding check: if the second node is two-connected between two nodes and the frame has been received from one of the two nodes, forwarding the frame to the other of the two nodes; and if the second node is more than two-connected, processing the frame in the control plane before forwarding the frame to another node.
An Ethernet network uses a link-state protocol (like OSPF or IS-IS) and supports data plane multicasting. When a node detects a topology change (e.g., a link goes down), it sends a control message in a multicast frame to a special control plane multicast group address. Nodes receiving this frame check if it arrived on the expected port using a reverse path forwarding (RPF) check. If the RPF check fails, the frame is discarded to prevent routing loops. If the RPF check passes and the node is connected to only two other nodes, it forwards the frame to its other neighbor. If the receiving node is connected to more than two nodes, it processes the frame in the control plane before forwarding it.
2. The link state protocol controlled Ethernet network of claim 1 , wherein the control message is a link state routing protocol control message.
The Ethernet network from the previous description uses a link state routing protocol control message as the control message signifying a local topology change. This means the control message indicating the network change is specifically formatted according to the link state routing protocol in use (e.g., an OSPF Link State Advertisement or IS-IS Link State PDU). This specific type of control message triggers the failure notification mechanism described in the previous description.
3. The link state protocol controlled Ethernet network of claim 1 , wherein the control plane specific multicast group address is a source specific multicast address.
The Ethernet network from the initial network description uses a source-specific multicast (SSM) address as the control plane multicast group address. This means the multicast group address is associated with a specific source (the node originating the topology change notification). Using SSM allows receivers to subscribe to traffic only from known sources, improving security and efficiency compared to Any-Source Multicast.
4. The link state protocol controlled Ethernet network of claim 1 , wherein the second node is configured to select a plurality of downstream nodes to which the frame is to be forwarded using a shortest path tree rooted on the first node.
The Ethernet network from the initial network description allows a receiving node to select which downstream nodes receive the topology change notification. It does this by computing a shortest-path tree rooted at the node that initially detected the topology change. The receiving node then only forwards the notification to nodes that are part of this shortest-path tree. This limits the scope of the multicast and reduces network congestion by only forwarding the frame to relevant nodes.
5. The link state protocol controlled Ethernet network of claim 1 , wherein the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned to control message exchange.
The Ethernet network from the initial network description utilizes a (*,G) multicast address, which is a multicast address common to all nodes and assigned specifically for control message exchange. This means all nodes in the network are configured to listen to this well-known multicast group address for topology change notifications.
6. The link state protocol controlled Ethernet network of claim 1 , wherein the second node is configured to acknowledge the frame to a first node when the frame passes the reverse path forwarding check.
The Ethernet network from the initial network description requires a node receiving a topology change notification to acknowledge the frame to the originating node if the reverse path forwarding check passes. This provides a mechanism for the originating node to confirm that its notification has been received by at least one other node in the network, improving the reliability of the notification process.
7. The link state protocol controlled Ethernet network of claim 6 , wherein the second node is configured to acknowledge the frame to the first node only when the second node is two-connected between the first node and a third node.
The Ethernet network from the previous description with acknowledgements specifies that a receiving node only acknowledges the topology change notification if it is two-connected between the originating node and another node. If the receiving node has more than two connections, it does not send an acknowledgement. This focuses acknowledgements on simpler network topologies like ring networks, where two-connected nodes are common, and reduces the amount of acknowledgement traffic in more complex topologies.
8. A node for a link state protocol controlled Ethernet network having a data plane multicast capability, the node comprising: a routing element configured to receive a frame containing a control message signifying a local topology change, the frame being issued by a first other node of the network and being addressed to a control plane specific multicast group address; and a reverse path forwarding check element configured: to perform a reverse path forwarding check on the frame to determine if the frame arrived at the node on a port expected for multicast frames issued by the first other node; to discard the frame immediately when the frame fails the reverse path forwarding check; and when the frame passes the reverse path forwarding check: when the second node is two-connected between two nodes and the frame has been received from one of the two nodes, to forward the frame to the other of the two nodes; and when the second node is more than two-connected, to process the frame in the control plane before forwarding the frame to another node.
A network node for an Ethernet network supporting data plane multicasting has a routing element and a reverse path forwarding (RPF) check element. The routing element receives a control message (a frame) indicating a topology change, sent by another node to a control plane multicast group address. The RPF element verifies that the frame arrived on the expected port. Frames failing the RPF check are discarded. If the RPF check passes and the node is two-connected, the frame is forwarded to its other neighbor. If the node has more than two connections, the frame is processed in the control plane before forwarding.
9. The node of claim 8 , wherein the control message is a link state routing protocol control message.
The network node from the previous node description uses a link state routing protocol control message as the control message signifying a local topology change. This means the control message indicating the network change is specifically formatted according to the link state routing protocol in use (e.g., an OSPF Link State Advertisement or IS-IS Link State PDU).
10. The node of claim 8 , wherein the control plane specific multicast group address is a source specific multicast address.
The network node from the previous node description uses a source-specific multicast (SSM) address as the control plane multicast group address. This means the multicast group address is associated with a specific source (the node originating the topology change notification). Using SSM allows receivers to subscribe to traffic only from known sources, improving security and efficiency compared to Any-Source Multicast.
11. The node of claim 8 , configured to select a plurality of downstream nodes to which the frame is forwarded using a shortest path tree rooted on the first other node.
This invention describes a network node designed for a link state protocol-controlled Ethernet network that supports data plane multicast. This node is configured to receive a network frame containing a control message, which signals a local topology change. The frame originates from another node in the network and is addressed to a specific multicast group used for control plane communications. Upon receiving the frame, the node performs a Reverse Path Forwarding (RPF) check. This check determines if the frame arrived on the expected port for multicast traffic from the original sending node. If the RPF check fails, the frame is immediately discarded. If it passes, the node's actions depend on its connectivity: if it's connected to only two other nodes and received the frame from one, it forwards it to the other connected node. If it's connected to more than two nodes, it processes the control message in its control plane before forwarding it further. A key feature is that this node is configured to select multiple downstream nodes for forwarding by calculating a shortest path tree, using the original sending node as the root of this tree, ensuring efficient distribution of the topology change information.
12. The node of claim 8 , wherein the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned to control message exchange.
The network node from the initial node description is configured such that the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned specifically for control message exchange. This means all nodes in the network are configured to listen to this well-known multicast group address for topology change notifications.
13. The node of claim 8 , configured to acknowledge the frame to the first other node when the frame passes the reverse path forwarding check.
The network node from the initial node description is configured to send an acknowledgement back to the originating node when the topology change notification frame passes the reverse path forwarding check. This provides feedback to the originating node, confirming that its notification has been received and processed by at least one other node in the network.
14. The link state protocol controlled Ethernet network of claim 13 , configured to acknowledge the frame to the first other node only when the node is two-connected between the first other node and a second other node.
The network node from the previous description regarding acknowledgements is configured to only send an acknowledgement if it is two-connected between the originating node and another node. This limits acknowledgements to simpler network topologies, such as ring networks, and avoids generating unnecessary acknowledgement traffic in more complex network configurations.
15. A method of operating a node for a link state protocol controlled Ethernet network having a data plane multicast capability, the method comprising: receiving a frame containing a control message signifying a local topology change, the frame being issued by a first other node of the network and being addressed to a control plane specific multicast group address; and performing a reverse path forwarding check on the frame to determine if the frame arrived at the second node on a port expected for multicast frames issued by the first other node; discarding the frame immediately when the frame fails the reverse path forwarding check; and when the frame passes the reverse path forwarding check: if the second node is two-connected between two nodes and the frame has been received from one of the two nodes, forwarding the frame to the other of the two nodes; and if the second node is more than two-connected, processing the frame in the control plane before forwarding the frame to another node.
A method for operating a node in an Ethernet network with data plane multicasting involves receiving a frame containing a control message indicating a topology change. The frame is sent by another node to a control plane multicast group address. The method performs a reverse path forwarding (RPF) check to ensure the frame arrived on the expected port. If the RPF check fails, the frame is discarded. If the RPF check passes and the node is two-connected, the frame is forwarded to its other neighbor. If the node has more than two connections, the frame is processed in the control plane before forwarding.
16. The method of claim 15 , wherein the control message is a link state routing protocol control message.
The method described in the previous description uses a link state routing protocol control message as the control message signifying a local topology change. This means the control message indicating the network change is specifically formatted according to the link state routing protocol in use (e.g., an OSPF Link State Advertisement or IS-IS Link State PDU).
17. The method of claim 15 , wherein the control plane specific multicast group address is a source specific multicast address.
The method described in the initial method description uses a source-specific multicast (SSM) address as the control plane multicast group address. This means the multicast group address is associated with a specific source (the node originating the topology change notification). Using SSM allows receivers to subscribe to traffic only from known sources, improving security and efficiency compared to Any-Source Multicast.
18. The method of claim 15 , comprising selecting a plurality of downstream nodes to which the frame is forwarded using a shortest path tree rooted on the first other node.
The method described in the initial method description includes selecting a plurality of downstream nodes to which the frame is forwarded using a shortest path tree rooted on the first other node. This limits the scope of the multicast and reduces network congestion by only forwarding the frame to relevant nodes.
19. The method of claim 15 , wherein the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned to control message exchange.
The method described in the initial method description utilizes a (*,G) multicast address, which is a multicast address common to all nodes and assigned specifically for control message exchange. This means all nodes in the network are configured to listen to this well-known multicast group address for topology change notifications.
20. The method of claim 15 , comprising acknowledging the frame to the first other node when the frame passes the reverse path forwarding check.
The method described in the initial method description includes acknowledging the frame to the originating node when the frame passes the reverse path forwarding check. This provides a mechanism for the originating node to confirm that its notification has been received by at least one other node in the network, improving the reliability of the notification process.
21. The method of claim 20 , comprising acknowledging the frame to the first other node only when the node is two-connected between the first other node and a second other node.
The method described in the previous description with acknowledgements includes acknowledging the frame to the originating node only when the node is two-connected between the originating node and another node. If the receiving node has more than two connections, it does not send an acknowledgement. This focuses acknowledgements on simpler network topologies like ring networks, where two-connected nodes are common, and reduces the amount of acknowledgement traffic in more complex topologies.
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November 11, 2014
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